For several thousand years wind turbines have been used as prime power movers in raising water or powering mills grinding grains. Just after the turn of the 19th Century into the 20th Century, before the First World War, perhaps a million open fan wind turbines were in use within the US alone, pumping water in farms and ranches all over America.
In the late 20th Century, and the beginning 21st Century, rising fuel costs, and increased concern for global pollution and warming have raised wind power generally to the fastest growing renewable energy source on the planet. A recent Stanford University study shows that North America has more sites suitable for locating modern open fan wind turbines than any other continent in the world today. However, modern large open fan wind turbines have certain characteristics and problems in the process of becoming more apparent as the installation base of such turbines increases,
In the Altamont, in California, as an example, the open fan wind turbines there kill over one thousand hawks and eagles each year, from collisions between the fan blades and the birds. From an economic point of view, large open fan wind turbine installations are best sited in areas of high wind, which often have a low human population because of the wind; areas in the Dakotas, Kansas, and Texas are a good example. Thus the wind turbine installations must be accompanied by expensive, complete electrical utility infrastructures, and the generated electrical power expensively shipped via high tension lines to the eventual power consumers.
In European countries, such as England, having high quality wind resources, and a large installed large open fan wind turbine base, the location of very visible open fan wind turbines is interfering with aesthetic sight line values concerning tourists. The sightlines to Wordsworth's cottage in Grasmere, in the Lake Country, as an example, are best not obscured and blocked by large open fan wind turbines, from a tourist point of view.
The following patents reflect the state of the art of which the applicant is aware, and are included herewith to discharge applicant's duty to disclose relevant prior art. The stipulation follows, however, that none of the cited patents teach singly, or in combination, nor render obvious when considered in any conceivable combination, the central ideas, or nexus of the present, instant invention, as disclosed in greater detail hereinafter, and as particularly claimed.
PATENT NUMBERINVENTORISSUE DATE969,587W. A WilliamsSep. 6, 19103,706,430Floyd FoglemanDec. 19, 1972Richard Kline4,046,338Floyd FoglemanSep. 6, 1977Richard Kline4,075,500Richard A. OmanFeb. 21, 1978Kenneth M. Foreman4,084,918Vladimir H. PavlecaApr. 18, 19784,143,992Charles W. CrookMar. 13, 19794,174,923Glen A. WilliamsonNov. 20, 19794,191,505John W. KaufmanMar. 4, 19804,238,171Bernard Van MechelenDec. 9, 19804,279,569Gary J. HarloffJul. 21, 19815,009,569Francis N. HectorApr. 23, 1991Junior and SeniorU.S. Pat. No. 6,638,005 B2John W. HolterOct. 28, 2003Eric G. HolterU.S. 2004/0156710 A1Christopher Norman GaskelAug. 12, 2004patent applicationPublication
Each one of these cited patents can be characterized as providing some form of enclosure for an otherwise open fan, and as providing some form of augmentation to the intake air mass, or as providing the suppression of fan blade vortices, which a shroud normally provides in conjunction with an open fan.